// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_ANDROID_JNI_INT_WRAPPER_H_
#define BASE_ANDROID_JNI_INT_WRAPPER_H_

// Wrapper used to receive int when calling Java from native.
// The wrapper disallows automatic conversion of long to int.
// This is to avoid a common anti-pattern where a Java int is used
// to receive a native pointer. Please use a Java long to receive
// native pointers, so that the code works on both 32-bit and 64-bit
// platforms. Note the wrapper allows other lossy conversions into
// jint that could be consider anti-patterns, such as from size_t.

// Checking is only done in debugging builds.

#ifdef NDEBUG

typedef jint JniIntWrapper;

// This inline is sufficiently trivial that it does not change the
// final code generated by g++.
inline jint as_jint(JniIntWrapper wrapper)
{
    return wrapper;
}

#else

class JniIntWrapper {
public:
    JniIntWrapper()
        : i_(0)
    {
    }
    JniIntWrapper(int i)
        : i_(i)
    {
    }
    JniIntWrapper(const JniIntWrapper& ji)
        : i_(ji.i_)
    {
    }
    template <class T>
    JniIntWrapper(const T& t)
        : i_(t)
    {
    }
    jint as_jint() const { return i_; }

private:
    // If you get an "is private" error at the line below it is because you used
    // an implicit conversion to convert a long to an int when calling Java.
    // We disallow this, as a common anti-pattern allows converting a native
    // pointer (intptr_t) to a Java int. Please use a Java long to represent
    // a native pointer. If you want a lossy conversion, please use an
    // explicit conversion in your C++ code. Note an error is only seen when
    // compiling on a 64-bit platform, as intptr_t is indistinguishable from
    // int on 32-bit platforms.
    JniIntWrapper(long);
    jint i_;
};

inline jint as_jint(const JniIntWrapper& wrapper)
{
    return wrapper.as_jint();
}

#endif // NDEBUG

#endif // BASE_ANDROID_JNI_INT_WRAPPER_H_
